Each slider member of a printing mechanism of the foregoing type customarily has a hammer face at its forward end, a bumper surface at its rearward end, and armature elements intermediate its length. The hammer face engages a print band of the like during each electromagnetically-induced stroke of forward movement of the slider, and the bumper surface engages a damper pad of the associated spring-damper unit upon spring-induced return movement of the slider in a rearward direction to an inactive position. For optimum performance the hammer faces of the sliders should be in substantial lateral alignment when the sliders occupy their inactive positions, and each forward stroke of slider movement should be of minimum duration or "flight time" and should generate an impact force of maximum magnitude between the hammer face of the slider and the print band. The flight time and impact force attendant each forward stroke of slider movement are affected by and dependent in significant part upon the relative longitudinal positional relationship present between the pole faces of the electromagnets and the armature elements of the slider when the slider occupies its inactive position. The inactive position occupied by the slider is determined by the location of the damper pad of the spring-damper unit associated with the slider, and may be varied in a longitudinal direction by adjustment of the unit when it is capable of adjustive movement in such direction.
Positional adjustment of the spring-damper units may be employed either to laterally align the hammer faces of the sliders or to optimize their strokes of forward movement, but not for both purposes. Adjustment of the units for the former purpose does not also result in optimization of the forward strokes of slider movement, and adjustment of the units for the later purpose leaves the hammer faces of the sliders laterally nonaligned. One previously proposed way of correcting misalignment of the hammer faces has been by subjecting them to a grinding operation after positional adjustment of the spring-damper units has been completed. This method of effecting lateral alignment between the hammer faces is time-consuming and costly, and additionally risks introduction into the print mechanism of metallic particles detrimental to its operation. The foregoing procedure is highly unsatisfactory, and there is a need for a print mechanism of the linear actuator type in which the desired lateral alignment of the slider hammer faces and optimization of the forward strokes of movement the sliders can be efficiently, economically and clearly achieved.